Electrolytic device and electrode

ABSTRACT

According to one embodiment, an electrolytic device includes an electrolytic cell including a first electrode, a second electrode opposing the first electrode and a diaphragm provided between the first electrode and the second electrode. The first electrode is formed of a plate including a first surface opposing the diaphragm, a second surface located on an opposite side to the diaphragm, and first recess portions formed in the first surface with a first pattern. The first recess portions include a bottom surface apart from the first surface and through-holes opening to the second surface of the first electrode and to a part of the bottom surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation application of PCT Application No.PCT/JP2015/075626, filed Sep. 9, 2015 and based upon and claiming thebenefit of priority from Japanese Patent Application No. 2014-191565,filed Sep. 19, 2014, the entire contents of all of which areincorporated herein by reference.

FIELD

Embodiments described herein relate generally to an electrolytic deviceand an electrode used for the electrolytic device.

BACKGROUND

As an electrolytic device, an electrolyzed-water production device forproducing ionized alkaline water, ozone water, aqueous hypochlorous acidor the like is conventionally known. As the electrolyzed-waterproduction device, a device comprising a three-chamber electrolytic tank(electrolytic cell) has been proposed. The three-chamber cell includesan electrolytic container divided into three chambers, that is, an anodechamber, an intermediate chamber and a cathode chamber by diaphragms. Insuch an electrolytic device, for example, salt water is introduced intothe intermediate chamber, and water is introduced into the cathodechamber and the anode chamber on the right and left sides. Thus, thesalt water in the intermediate chamber is electrolyzed by the anode andthe cathode to produce aqueous hypochlorous acid from gaseous chlorineproduced in the anode chamber and sodium hydroxide solution in thecathode chamber. Hypochlorous acid thus produced can be utilized assterilizing solution and sodium hydroxide solution as a cleaningsolution.

However, an electrolytic device having such a three-chamber cellinvolves reactions in a complicated way around the anode, which proceedfrom chlorine ions to gaseous chloride and then to hypochlorous acid.Here, if the reaction system does not take place appropriately,competitive gaseous oxygen is produced and thus the productivity ofhypochlorous acid is reduced. Further, gaseous chloride and hypochlorousacid produced here are strong oxidizers, which may cause deteriorationof diaphragms.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram schematically showing an electrolytic deviceaccording to a first embodiment.

FIG. 2 is an exploded perspective view showing an electrolytic cell ofthe electrolytic device according to the first embodiment.

FIG. 3 is a sectional view of the electrolytic cell.

FIG. 4 is an expanded perspective view showing a first electrode and ananode cover of the electrolytic cell.

FIG. 5 is a perspective view showing a first surface side of the firstelectrode.

FIG. 6 is a perspective view showing a second surface side of the firstelectrode.

FIG. 7 is a partially expanded perspective view showing the firstelectrode.

FIG. 8 is a plan view of the first electrode as viewed from the firstsurface side.

FIG. 9 is a sectional view of the first electrode and an anion-exchangemembrane, taken along line A-A of FIG. 8.

FIG. 10 is a sectional view of the first electrode and theanion-exchange membrane, taken along line B-B of FIG. 8.

FIG. 11 is a partially expanded perspective view showing a firstelectrode of an electrolytic device according to a first modification.

FIG. 12 is a plan view of the first electrode according to the firstmodification as viewed from the first surface side.

FIG. 13 is a sectional view of the first electrode and an anion-exchangemembrane, taken along line C-C of FIG. 12.

FIG. 14 is a sectional view of the first electrode and an anion-exchangemembrane, taken along line D-D of FIG. 12.

FIG. 15 is a partially expanded perspective view showing a firstelectrode of an electrolytic device according to a second modification.

FIG. 16 is a plan view of the first electrode according to the secondmodification as viewed from the first surface side.

FIG. 17 is a sectional view of the first electrode and an anion-exchangemembrane, taken along line E-E of FIG. 16.

FIG. 18 is a sectional view of the first electrode and an anion-exchangemembrane, taken along line F-F of FIG. 16.

FIG. 19 is a partially expanded perspective view showing a firstelectrode of an electrolytic device according to a third modification.

FIG. 20 is a plan view of the first electrode according to the thirdmodification as viewed from the first surface side.

FIG. 21 is a sectional view of the first electrode and an anion-exchangemembrane, taken along line G-G of FIG. 20.

FIG. 22 is a sectional view of the first electrode and an anion-exchangemembrane, taken along line H-H of FIG. 20.

FIG. 23 is a partially expanded perspective view showing a firstelectrode of an electrolytic device according to a fourth modification.

FIG. 24 is a partially expanded perspective view showing a firstelectrode of an electrolytic device according to a fifth modification.

FIG. 25 is a partially expanded perspective view showing a firstelectrode of an electrolytic device according to a sixth modification.

FIG. 26 is a partially expanded perspective view showing a firstelectrode of an electrolytic device according to a seventh modification.

FIG. 27 is a plan view of the first electrode according to the seventhmodification as viewed from the first surface side.

FIG. 28 is a sectional view of the first electrode and an anion-exchangemembrane, taken along line I-I of FIG. 27.

FIG. 29 is a partially expanded perspective view showing a firstelectrode of an electrolytic device according to an eighth modification.

FIG. 30 is a plan view of the first electrode according to the eighthmodification as viewed from the first surface side.

FIG. 31 is a sectional view of the first electrode and an anion-exchangemembrane, taken along line J-J of FIG. 30.

DETAILED DESCRIPTION

Various embodiments will be described below with reference to theaccompanying drawings. In general, according to one embodiment, anelectrolytic device comprises an electrolytic cell comprising a firstelectrode, a second electrode opposing the first electrode and at leastone diaphragm provided between the first electrode and the secondelectrode. The first electrode is formed of a plate comprising a firstsurface opposing the diaphragm, a second surface located on an oppositeside to the diaphragm, and first recess portions formed in the firstsurface with a first pattern. The first recess portions include a bottomsurface apart from the first surface and through-holes each opening tothe second surface of the first electrode and to a part of the bottomsurface.

Throughout the embodiments, common structural members are designated bythe same reference symbols, and the explanation therefor will not berepeated. Further, the drawings are schematic diagrams designed toassist the reader to understand the embodiments easily. Thus, there maybe sections where the shape, dimensions, ratio, etc. are different fromthose of the actual devices, but they can be re-designed as needed withreference to the following explanations and publicly known techniques.

First Embodiment

FIG. 1 is a diagram briefly showing an electrolytic device according tothe first embodiment. In this embodiment, the electrolytic device 10 isconstituted as an electrolysis water production device. The electrolyticdevice 10 comprises, as shown in FIG. 1, a three-chamber electrolyticcell 11. The electrolytic cell 11 is formed into a flat rectangle box,inside of which is divided by an anion-exchange membrane 16 as a firstdiaphragm and a cation-exchange membrane 18 as a second diaphragm intoan intermediate chamber 15 a, and also an anode chamber 15 b and acathode chamber 15 c located on both sides of the intermediate chamber15 a. A first electrode (anode) 14 is provided in the anode chamber 15 bso as to oppose the anion-exchange membrane 16. A second electrode(cathode) 20 is provided in the cathode chamber 15 c so as to oppose thecation-exchange membrane 18.

The electrolytic device 10 comprises an electrolyte supplier 19 whichsupplies an electrolyte, for example, saturated salt water, to theintermediate chamber 15 a of the electrolytic cell 11, a water supplier21 which supplies a solution to be electrolyzed, for example, water, tothe anode chamber 15 b and the cathode chamber 15 c and a power supply23 that applies positive and negative voltages respectively to the firstand second electrodes 14 and 20.

The electrolyte supplier 19 comprises a salt water tank 25 to producesaturated salt water, a supply pipe 19 a which conveys saturated saltwater from the salt water tank 25 to a lower portion of the intermediatechamber 15 a, a liquid feed pump 29 provided in the supply pipe 19 a anda drainage pipe 19 b which sends the electrolyte which has flowedthrough the inside of the intermediate chamber 15 a from an upperportion of the intermediate chamber 15 a to the salt water tank 25.

The water supplier 21 comprises a water supply source (not shown) whichsupplies water, a water supply pipe 21 a which guides water to lowerportions of the anode chamber 15 b and the cathode chamber 15 c from thewater supply source, a first drainage pipe 21 b to discharge the waterwhich has flowed through the anode chamber 15 b from an upper portion ofthe anode chamber 15 b, a second drainage pipe 21 c to discharge thewater which has flowed through the cathode chamber 15 c from an upperportion of the cathode chamber 15 c and a gas-liquid separator 27provided in the second drainage pipe 21 c.

The operation of the electrolytic device 10 configured as describedabove, which actually electrolyzes salt water to produce an acidicsolution (aqueous hypochlorous acid and hydrochloric acid) and alkalinewater (sodium hydroxide) will now be described.

As shown in FIG. 1, the liquid feed pump 29 is operated to supplysaturated salt water to the intermediate chamber 15 a of theelectrolytic cell 11, and water to the anode chamber 15 b and thecathode chamber 15 c. At the same time, a positive voltage and anegative voltage are applied to the first electrode 14 and the secondelectrode 20, respectively, from the power supply 23. Sodium ionselectrolytically dissociated in the salt water which has flowed into theintermediate chamber 15 a are attracted towards the second electrode 20,pass through the cation-exchange membrane 18 and flow into the cathodechamber 15 c. Then, in the cathode chamber 15 c, water is electrolyzedby the second electrode 20 and gaseous hydrogen and an aqueous solutionof sodium hydroxide are obtained. The aqueous solution of sodiumhydroxide and gaseous hydrogen thus produced flow out of the cathodechamber 15 c into the second drainage pipe 21 c, and are then separatedinto an aqueous solution of sodium hydroxide and gaseous hydrogen by thegas-liquid separator 27. The aqueous solution of sodium hydroxide(alkaline water) is discharged through the second drainage pipe 21 c.

Meanwhile, chlorine ions electrolytically dissociated in the salt waterin the intermediate chamber 15 a are attracted towards the firstelectrode 14, pass through the anion-exchange membrane 16 and flow intothe anode chamber 15 b. Then, the chlorine ions give electrons to theanode with the first electrode 14 to produce gaseous chlorine. Afterthat, the gaseous chlorine reacts with water in the anode chamber 15 bto produce hypochlorous acid and hydrochloric acid. The acidic solutionthus produced (aqueous hypochlorous acid and hydrochloric acid) isdischarged from the anode chamber 15 b through the first liquid drainagepipe 21 b.

Next, the structure of the electrolytic cell 11 will now be described inmore detail. FIG. 2 is an exploded perspective view of the electrolyticcell, and FIG. 3 is a sectional view thereof. As shown in FIGS. 2 and 3,the electrolytic cell 11 comprises an intermediate frame 22 of arectangular frame shape, which functions as a diaphragm, an anode cover(first cover member) 24 of a rectangular plate shape having outerdimensions substantially equal to those of the intermediate frame 22,which covers one side surface of the intermediate frame, and a cathodecover (second cover member) 26 of a rectangular plate shape having outerdimensions substantially equal to those of the intermediate frame 22,which covers the other side surface of the intermediate frame.

The anion-exchange membrane 16 is disposed between the intermediateframe 22 and the anode cover 24, as a first diaphragm to separate theintermediate chamber 15 a and the anode chamber 15 b from each other,and the first electrode (anode plate) 14 is disposed near theanion-exchange membrane 16 in the anode chamber 15 b. The cationexchange membrane 18 is disposed between the intermediate frame 22 andthe cathode cover 26, as a second diaphragm to separate the intermediatechamber 15 a and the cathode chamber 15 c from each other, and thesecond electrode (cathode) 20 is disposed near the cation-exchangemembrane 18 in the cathode chamber 15 c.

A first inlet 34 communicating with the intermediate chamber 15 a isformed in a lower end of the intermediate frame 22 and a first outlet 36communicating with the intermediate chamber 15 a is provided in an upperend thereof. The supply pipe 19 a and the drainage pipe 19 b areconnected to the first inlet 34 and the first outlet 36, respectively.

As shown in FIGS. 2 to 4, a plurality of linear ribs 33 are provided onan inner surface of the anode cover 24, to extend in, for example, thevertical direction (the second direction Y). The ribs 33 are arrangedparallel to each other while keeping a predetermined gap betweenadjacent ones. Between each adjacent pair of the ribs 33, a circulationgroove 32 a is provided to extend in the vertical direction. Further, apair of upper and lower side grooves by which ends of each circulationgroove 32 a communicate are formed in the inner surface of the anodecover 24. The anode chamber 15 b is defined by the circulation grooves32 a, the side grooves and the anion-exchange membrane 16. In addition,the circulation grooves 32 a and the side grooves form flow paths forwater.

A second inlet 37 communicating with the lower end of the circulationgrooves 32 a is formed in a lower portion of the anode cover 24, and asecond outlet 38 communicating with the upper end of the circulationgrooves 32 a is formed in an upper portion of the anode cover 24. Thesupply pipe 21 a and the first drainage pipe 21 b are connected to thesecond inlet 37 and the second outlet 38, respectively.

A plurality of ribs 35, circulation grooves 32 b, and side grooves areeach formed on an inner surface of the cathode cover 26 so as to extendin the perpendicular direction (the second direction Y). The circulationgrooves 32 b, the side grooves and the cation-exchange membrane 18defines the cathode chamber 15 c. Further, the circulation grooves 32 band the side grooves form a flow path for water to flow.

A third inlet 39 communicating with the lower end of the circulationgrooves 32 b is formed in a lower portion of the cathode cover 26, and athird outlet 41 communicating with the upper end of the circulationgrooves 32 a is formed in an upper portion thereof. The supply pipe 21 aand the second drainage pipe 21 c are connected to the third inlet 39and the third outlet 41, respectively.

As shown in FIGS. 2 and 3, frame-shaped sealing materials 40 forpreventing leakage are disposed respectively between structuralcomponents, that is, between the peripheral portion of the anode cover24 and the peripheral portion of the first electrode 14; between theperipheral portions of the first electrode 14 and the anion-exchangemembrane 16 and the intermediate frame 22; between the intermediateframe 22 and the peripheral portions of the second electrode 20 and thecation-exchange membrane 18; and between the peripheral portion of thesecond electrode 20 and the peripheral portion of the cathode cover 26.

A plurality of fixing bolts 50 are inserted through the peripheralportions of these structural components from, for example, the anodecover 24 side and the tip portions project from the cathode cover 26. Anut 52 is screwed into the tip portion of each fixing bolt 50. With thefixing bolts 50 and the nuts 52 as fastening components, the peripheralportions of the structural components are fastened respectively witheach other to maintain the water tightness of the intermediate chamber15 a, the anode chamber 15 b and the cathode chamber 15 c.

As shown in FIGS. 2 and 3, the anion-exchange membrane 16 and thecation-exchange membrane 18 are each formed into a thin rectangularplate having an outer size substantially equal to that of theintermediate frame 22 and a thickness of about 100 to 200 μm. Theanion-exchange membrane 16 and the cation-exchange membrane 18 each havecharacteristics of passing only specific ions. A plurality ofthrough-holes through which the fixing bolts 50 are inserted are formedin the peripheral portions of the anion-exchange membrane 16 and thecation-exchange membrane 18.

The anion-exchange membrane 16 is disposed to oppose one surface side ofthe intermediate frame 22, and the peripheral portion thereof is tightlyattached to the intermediate frame 22 through the sealing material 40.Similarly, the cation-exchange membrane 18 is disposed to oppose theother surface side of the intermediate frame 22 and the peripheralportion thereof is tightly attached to the intermediate frame 22 throughthe sealing material 40. Note that the first diaphragm and the seconddiaphragm may be formed from not only an ion-exchange membrane but aporous membrane having water permeability.

The first electrode 14 and the second electrode 20 are each formed froma metal plate having a thickness of about 1 mm, formed into arectangular shape having an outer size substantially equal to that ofthe intermediate frame 22. The first electrode 14 and the secondelectrode 20 each have a central portion (effective region) wheremicro-through-holes for passing liquid are formed, and a peripheralportion in which a plurality of through-holes through which fixing bolts50 are inserted are formed. The first electrode 14 includes a contactterminal 14 b projecting from a side edge thereof. Similarly, the secondelectrode 20 includes a contact terminal 20 b projecting from a sideedge thereof.

The first electrode 14 is arranged to oppose to and be tightly contactwith the anion-exchange membrane 16. The second electrode 20 is arrangedto oppose to and be tightly contact with the cation-exchange membrane18.

Next, the structure of the first electrode (anode) 14 will be describedin detail as a typical example of the electrodes.

FIG. 4 is an expanded perspective view of the first electrode and theanode cover. FIG. 5 is a perspective view of the first surface side ofthe first electrode. FIG. 6 is a perspective view of the second surfaceside of the first electrode. FIG. 7 is a partially expanded perspectiveview of the first electrode. FIG. 8 is a plan view of the firstelectrode as viewed from the first surface side. FIG. 9 is a sectionalview of the first electrode and the anion-exchange membrane, taken alongline A-A of FIG. 8. FIG. 10 is a sectional view of the first electrodeand the anion-exchange membrane, taken along line B-B of FIG. 8.

As shown in FIG. 4 to FIG. 7, the first electrode 14 has, for example, aporous, mesh structure in which a great number of recesses andthrough-holes are made in a matrix 17 of a rectangular metal plate. Thematrix 17 includes a first surface 17 a and a second surface 17 bopposing substantially parallel to the first surface 17 a. The distancebetween the first surface 17 a and the second surface 17 b, that is, theplate board thickness T, is, for example 0.8 mm. The first surface 17 aopposes the first diaphragm 16 and the second surface 17 b opposes theanode cover 24. The matrix 17 may be made from a metal such as titanium.

In the first surface 17 a of the matrix 17, a first recess R1 having afirst pattern is formed over the entire surface. In the second surface17 b of the matrix 17, a second recess R2 having a second patterndifferent from the first pattern is formed over the entire surface.

In this embodiment, the first recess R1 of the first pattern comprises aplurality of thin linear first recess portions 42 formed in the firstsurface 17 a of the matrix 17 and the first recess portions 42 are eachopened in the first surface 17 a. Each of the first recess portions 42includes a bottom surface (bottom portion) 42 a which is apart from thefirst surface 17 a, that is, recessed from the first surface 17 a by apredetermined depth. The second recess R2 of the second patterncomprises a plurality of thick or coarse linear second recess portions44 formed in the second surface 17 b of the matrix 17 and the secondrecess portions 44 are each opened to the second surface 17 b. The firstrecess portions 42 and the second recess portions 44 are formed in theentire rectangular effective region excluding the peripheral portion ofthe matrix 17. A plurality of first recess portions 42 communicate withone second recess 44 and each of the communicating portions forms athrough-hole 46. Each of the through-holes 46 opens to a part of thebottom surface 42 a of the first recess portion 42 and opens to thesecond surface 17 b of the matrix 17. The entire surface of the firstelectrode 14 is covered with an iridium oxide catalyst. The iridiumoxide catalyst produces a lower overvoltage in the gaseous chlorineproduction than in the competitive gaseous oxygen production, and ifthere are a certain number of chlorine ions around the anode, gaseouschlorine is selectively produced.

As shown in FIGS. 4 to 10, in this embodiment, the first recess portions42 are each formed into straight lines extending in the first directionX, for example, a horizontal direction. The first recess portions 42 arearranged to be parallel to one another. The first recess portions 42 areeach formed to be longer than an opening width W3 of the second recessportions 44, which will be described later. In this embodiment, thefirst recess portions 42 each extend continuously from one end to theother end of the effective region of the first surface 17 a (centralregion of the rectangular shape, excluding the peripheral portion on thefirst surface). An opening width W1 of the first recess portions 42 is,for example, 0.4 mm, a pitch P1 of the first recess portions 42 in thearranging direction Y is 0.5 mm, a depth D1 of the first recesses 42 isless than a half of the thickness T of the matrix 17, more specifically,for example, 0.1 to 0.2 mm. In this embodiment, the first recessportions 42 are each formed so as to widen from the bottom portion(bottom surface 42 a) side toward the first surface 17 a, morespecifically, to have substantially a trapezoidal shape in crosssection. The both side surfaces which define each first recess 42 extendwhile inclining with respect to the first surface 17 a. With thisstructure, some of the first recess portions 42 communicate with aplurality of second recess portions 44 by a through-width W2 of 0.2 mm.

In this embodiment, the second recess portions 44 on the second surface17 b side are formed in a straight line extending in a directioncrossing the first direction X, that is, for example, a second directionY orthogonal to the direction X. The second recess portions 44 arearranged to be parallel to each other. The second recess portions 44each extend from one end to the other end of the effective region(central region of the rectangular shape, excluding the peripheralportion on the second surface) of the second surface 17 b. An openingwidth W3 of the second recess portions 44 is sufficiently larger thanthe opening width W1 of the first recess portions 42, for example, 2.4mm, a pitch P2 of the second recess portions 44 in the arrangingdirection X is 3 mm, and a depth D2 of the second recess portions 44 isgreater than a half of the thickness T of the matrix 17, morespecifically, 0.6 to 0.7 mm. In this embodiment, the second recessportions 44 are each formed so as to widen from the bottom side towardthe second surface 17 b, more specifically, to have substantially atrapezoidal shape in cross section. The both side surfaces which defineeach second recess 44 42 extend while inclining with respect to thesecond surface 17 b. With this structure, the second recess portions 44communicate with a plurality of first recess portions 42 by athrough-width W4 of 1.2 mm.

The first electrode 14 configured as above can be produced by thefollowing procedure, for example. That is, the first surface 17 a andthe second surface 17 b of the matrix 17 are etched to be partially cutout, thus forming the first recess R1 of the first pattern and thesecond recess R2 of the second pattern. The cross-sections of the firstrecess portions 42 and the second recess portions 44 may be variousshapes, more specifically, not only a trapezoidal but also rectangular,semicircular, elliptical, arc-like and the like. Further, the angle madeby the first recess portions 42 and the second recess portions 44crossing therewith is not limited to right-angles, but may be any otherangles.

With the structure, the first recess portions 42 and the second recessportions 44 of the first electrode 14 communicate respectively with eachother at intersections to form a great number of through-holes 46. Thefirst surface 17 a opposing the first diaphragm 16 includes the most,more specifically, 80% of the surface opened by the first recessportions 42, and the area opened and made to communicate is set as lowas 16% of the surface area of the electrode. Further, in considerationof the collection of bubbles from the through-holes 46, the water flowis set in the width direction (the second direction Y) of thethrough-holes 46. As described, in this electrode, the matrix 17 isetched from both sides, namely, the first and second surfaces 17 a and17 b, and therefore it is possible to change the open aperture ratio ineach surface. Thus, this electrode can exhibit a function which cannotbe attained with the conventional electrode having the same openaperture ratio in both surfaces, manufactured by, for example, a die cutprocess. It is preferable here that the open area ratio of thethrough-holes 46 formed by the first recess portions 42 and the secondrecess portions 44 communicating with each other with respect to theentire area of the first surface 17 a be no more than a half of the openarea ratio of the first recess portions 42 to the entire area of thefirst surface.

Note that in this embodiment, the second electrode (cathode) 20 issimilar in structure to the first electrode 14.

As shown in FIGS. 3 and 4, the first electrode 14 is disposed in adirection where the extending direction Y of the second recess portions44 and the extending direction of the circulation grooves (flow paths)32 a of the anode cover 24 substantially coincide with each other. Thesecond surface 17 b of the first electrode 14 opposes the inner surfaceof the anode cover 24 and is in contact with the tip end surfaces of theribs 33. With this structure, water supplied to the anode chamber 15 bflows along the circulation grooves 32 a and the second recess portions44 of the first electrode 14, that is, in a direction crossing the firstrecess portions 42 of the first electrode 14.

Further, as shown in FIGS. 3, 9 and 10, the first surface 17 a of thefirst electrode 14 opposes and is tightly attached to the firstdiaphragm 16. Here, since the first recess portions 42 are formed inabout 80% of the effective region of the first surface 17 a, the bottomsurfaces 42 a of the first recess portions 42 are apart from the firstdiaphragm 16 and the first surface of the first electrode 14 by a depthof the first recess portion 42, which is 0.1 to 0.2 mm. As shown in FIG.10, the main reaction occurs at the bottom surfaces (bottom portions) 42a of the first recess portions 42, slightly apart from the firstdiaphragm 16, and hypochlorous acid, which is a produce, is collectedfrom the tiny gaps made by the first recess portions 42 through thethrough-holes 46 into the anode chamber 15 b. Thus, it is possible toachieve high production efficiency and prevention of degradation of thediaphragm both at the same time.

According to the electrolytic device 10 of the first embodiment, whichemploys the first electrode 14 having the above-described structure, anoutstanding advantageous effect can be obtained as compared to the caseof employing a conventional electrode formed by stamping (punchingprocess) or expanding after making nicks (expand/lath processing). Inother words, a great number of first recess portions 42 are formed inthe first surface 17 a which opposes the first diaphragm 16 of the firstelectrode 14 and therefore the first electrode 14 and the firstdiaphragm 16 can be set apart from each other by a slight distancewithout providing a separate member such as a spacer. With thisstructure, it is possible to improve the high production efficiency andthe anti-degradation of the diaphragm both at the same time.

With the conventional stamping process, an electrode is basically formedto include only through-holes made from the first to second surfaces 17a and 17 b with the same open area. Therefore, if the first electrode 14and the first diaphragm 16 are attached tightly to each other, the mainreaction occurs on the first surface 17 a which opposes the firstdiaphragm 16. Here, the first surface is tightly attached to the firstdiaphragm, a problem may arise, in which the diaphragm 16 is degraded byreaction products. Further, when the first surface and the firstdiaphragm are tightly attached, another problem may arise, in whichproducts produced by the electrolytic reaction cannot be collected, thusdegrading the efficiency.

In this embodiment, the first recess portions 42 (first recess R1) areformed in the first surface 17 a, which is the main reaction field, atan area ratio of high as 80%. With this structure, reaction products arequickly collected through a slight gap D1 (first recess portion 42) andthrough-holes 46 into the circulation grooves 32 a, thereby making itpossible to suppress degradation of the first diaphragm 16.

It is ideal that the first recess portions 42 have an open areaoccupying ratio as high as possible, but in practice, theabove-described effect can be sufficiently exhibited if they occupy 60%or more of the effective region of the first surface 17 a. Further, itis more effective if the pitch P1 of arrangement of the first recessportions 42 is finer to collect the products from the portions thereofwhich are in contact with the first diaphragm 16. In practice, theeffect can be sufficiently exhibited if the pitch P1 is 0.8 mm or less.It is ideal that the depth D1 of the first recess portions 42 is less aspossible, but in practice, the above-described effect can besufficiently exhibited if it is 0.5 mm or less. Further, if the minimumwidth of the region in the first surface 17 a of the first electrode 14is formed, is set to 0.3 mm or less, that is, the value obtained bysubtracting the opening width W1 of the first recess portions 42 fromthe arrangement pitch P1 of the first recesses 42 is 0.3 mm or less, itbecomes easy to collect the substances produced by the electrolyticreaction from the first surface 17 a tightly attached to the diaphragm.Thus, the above-described effect can be exhibited.

One of the functions of the second recess portions 44 of the firstelectrode 14 is to form the through-holes 46 for collecting the productsfrom the first recess portions 42 formed shallow at high precision tothe anode chamber 15 b side. Another function of the second recessportions 44 is to collect the current electrolyzed by the first recessportions 42 at lower resistance. To achieve this, the second recessportions 44 are formed to be coarse linear dent portions which cross thefirst recess portions 42. By crossing the first recess portions 42 andthe second recess portions 44 perpendicularly with each other, theintersections of the first recess portions 42 and the respective secondrecess portions 44 communicate with each other to extract hypochlorousacid or the like, produced in the first recess portions 42 from thethrough-holes 46 to the anode chamber 15 b side. Note that the arearatio of the through-holes 46 with respect to the area of the firstelectrode 14 is set as low as 16%. This is because the region of thefirst recess portions 42, lost by the through-holes 46 should be made assmall as possible. As the area of the through-holes 46 becomes larger,the number of chlorine ions lost by diffusion through the through-holes46 increases. For this reason, the area of the through-holes 46 shoulddesirably be set within 30% of the area of the electrode.

Further, in this embodiment, the first recess portions 42 and the secondrecess portions 44 are formed into a linear shape, whose longitudinaldirections cross each other orthogonally. With this structure, one firstrecess portion 42 communicate with a plurality of second recess portions44 to form a through-hole 46, thereby improving the drainage of thefirst recess portions 42 better than the case where the first recessportions 42 and the second recess portions 44 communicate with eachother one to one. That is, a plurality of through-holes 46 are providedin one second recess 44 without making a dead end, thus forming such astructure for reaction products, especially, air bubbles to easily passthrough. The linear second recess portions 44 are arranged to intersectperpendicularly with the first recess portions 42 at a coarse pitch soas to set the ratio of the area of the through-holes to as low as 16%while keeping the ratio of the open area of the first recesses 42 ashigh as 80%. Thus, the lowering of the concentration, which is caused bythe diffusion of the electrolyte from the through-holes 46, can beprevented without the first diaphragm 16 being degraded by the reactionproducts.

The second recess portions 44 are arranged at a coarse pitch P2 ofseveral millimeters, for example, 3 mm, so that the volume of the matrix17 remains at large and the current produced by electrolysis can besupplied at lower resistance. Further, the intensity of the electrodeitself can be maintained. In practice, the pitch P2 is set to 1 mm ormore to obtain a sufficient feed resistance.

As described above, according to the first embodiment, it is possible toprovide a long-life and efficient electrolytic device and an electrode,in which degradation of the diaphragm can be suppressed.

Next, the electrodes of electrolytic devices according to variousmodifications will be described.

Note that in the modifications described below, the elements which areidentical to those of the first embodiment are denoted by the samereference symbols, and parts different from those of the firstembodiment will be mainly described in detail.

(First Modification)

FIG. 11 is a partially expanded perspective view of the first electrodeaccording to the first modification. FIG. 12 is a plan view of the firstelectrode as viewed from the first surface side. FIG. 13 is a sectionalview of the first electrode and the anion-exchange membrane, taken alongline C-C of FIG. 12. FIG. 14 is a sectional view of the first electrodeand the anion-exchange membrane, taken along line D-D of FIG. 12.

As shown in FIG. 11 or FIG. 14, according to the first modification, thebasic specification of the first electrode 14 is the same as that of thefirst embodiment shown in FIGS. 4 to 10 except that the second recessportions 44 of the second recess portions R2 are formed thin to have anarrangement pitch P2 of 3 mm, as in the first embodiment, but an openingwidth W3 of 1.6 mm and a through-width W4 of 0.4 mm.

With the above-described structure, the area ratio of the through-holes46 is decreased to low as about 5%, thereby making it possible tofurther suppress the chlorine ions having passed through the firstdiaphragm 16 to diffuse in the circulation grooves 32 a. Thus, thechlorine ion concentration in the first surface 17 a of the firstelectrode 14 is increased to suppress the production of gaseous oxygen,thereby improving the production efficiency of acidic solution.

(Second Modification)

FIG. 15 is a partially expanded perspective view of the first electrodeaccording to the second modification. FIG. 16 is a plan view of thefirst electrode as viewed from the first surface side. FIG. 17 is asectional view of the first electrode and the anion-exchange membrane,taken along line E-E of FIG. 16. FIG. 18 is a sectional view of thefirst electrode and the anion-exchange membrane, taken along line F-F ofFIG. 16.

As shown in FIGS. 15 to 18, according to the second modification, aplurality of second recess portions 44 which constitute the secondrecess R2 formed in the second surface 17 b of the first electrode 14each extend in the second direction Y which intersects the firstdirection X perpendicularly, but are divided into a plurality ofsections without being continuous in the second direction. In otherwords, the second recess portions 44 of each row contain a plurality ofsegments of second recess portions 44 arranged in the second direction Yat a predetermined gap. The length of each segment of the second recessportions 44 in the second direction Y is equal to or greater than atotal of widths of two or more of the first recess portions 42. Further,the length of the first recess portions 42 is greater than the width W3of the second recess portions 44. With this configuration, theintersections of the first recess portions 42 and the second recessportions 44 communicate with each other to form a plurality ofthrough-holes 46. A plurality of first recess portions 42 communicatewith one segment of the second recess portions 44.

According to the second modification having the above-describedstructure, the second recess portions 44 of each row is divided into aplurality of segments so that wide linear portions remain betweenadjacent pairs of the segments of each second recess. With thisstructure, the mechanical strength is improved in all plane directionsof the first electrode 14, and also the anisotropy of the feedresistance of the first electrode can be relaxed.

Note that in the first embodiment described above, the second recessportions 44 are formed concurrently with the circulation grooves 32 a,but the first electrode 14 may be placed in the direction in which thesecond recess portions 44 intersect perpendicularly with the circulationgrooves 32 a.

(Third Modification)

FIG. 19 is a partially expanded perspective view of the first electrodeaccording to the third modification. FIG. 20 is a plan view of the firstelectrode as viewed from the first surface side. FIG. 21 is a sectionalview of the first electrode and the anion-exchange membrane, taken alongline G-G of FIG. 20. FIG. 22 is a sectional view of the first electrodeand the anion-exchange membrane, taken along line H-H of FIG. 20.

According to the third modification, the first electrode 14 comprises alarge number of first recess portions 42 formed in the first surface 17a, which constitute the first recess R1. The second recesses formed inthe second surface 17 b of the first electrode 14 are formed from thethrough-holes 47. That is, the through-holes 47 are opened in the firstsurface 17 a and the second surface 17 b of the matrix 17. Thethrough-holes 47 each have, for example, a circular shape whose diameteris larger than the width W1 of the first recess portions 42. In otherwords, the opening length of the through-holes 47 in the seconddirection Y is grater than the width W1 of the first recess portions 42.A plurality of first recess portions 42 communicate with onethrough-hole 47.

Since high precision is required, the first recess portions 42 of thefirst electrode 14 are formed by etching or photolithography, but thethrough-holes 47 as the second recesses are not so highly precise andmay be formed by the conventional punch process.

(Fourth Modification)

FIG. 23 is a partially expanded perspective view of the first electrodeaccording to the fourth modification. According to the fourthmodification, a plurality of first recess portions 42 which constitutethe first recess R1 formed in the first surface 17 a of the firstelectrode 14 each extend in the first direction X, but are divided intoa plurality of sections without being continuous in this direction. Inother words, the first recess portions 42 of each row contain aplurality of segments of first recess portions 42 arranged in the firstdirection X at a predetermined gap. The length of each segment of thefirst recess portions 42 is greater than the width W3 of the secondrecess portions 44. With this configuration, the intersections of thefirst recess portions 42 and the second recess portions 44 communicatewith each other to form a plurality of through-holes 46. A plurality ofsegments of first recess portions 42 communicate with a respectivesecond recess portion 44.

According to the fourth modification having the above-describedstructure, the first recess portions 42 of each row is divided into aplurality of segments so that linear portions remain between adjacentpairs of the segments of each first recess. With this structure, themechanical strength is improved in all plane directions of the firstelectrode 14, and also the anisotropy of the feed resistance of thefirst electrode can be relaxed.

(Fifth Modification)

FIG. 24 is a partially expanded perspective view of the first electrodeaccording to the fifth modification. The shape of the first recessportions 42 formed in the first surface 17 a of the first electrode 14is not limited to linear, but may be in some other shape. According tothe fifth modification, the first recess portions 42 formed in the firstsurface 17 a of the first electrode 14 are not linear, but extend alongthe direction X while being bent at two or more locations.

(Sixth Modification)

FIG. 25 is a partially expanded perspective view of the first electrodeaccording to the fifth modification. According to the fifthmodification, the first recess portions 42 which formed in the firstsurface 17 a of the first electrode 14 and constitute the first recessR1 extending along the first direction X to be curved or waved at two ormore locations.

(Seventh Modification)

FIG. 26 is a partially expanded perspective view showing the firstelectrode according to the seventh modification. FIG. 27 is a plan viewof the first electrode as viewed from the first surface side. FIG. 28 isa sectional view of the first electrode and the anion-exchange membrane,taken along line I-I of FIG. 27.

As shown in FIGS. 26 to 28, according to the seventh modification, thefirst recess R1 formed in the first surface 17 a of the first electrode14 include a plurality of third recess portions 45 in addition to thefirst recess portions 42. The third recess portions 45 are formed byforming a notch in at least one part of a wall portion which separatesadjacent pairs of first recesses 42 from each other. The third recessportions 45 are each opened in regions other than the through-holes 46in the first surface 17 a, so as to make adjacent pairs of first recessportions 42 communicate with each other. In this modification, the thirdrecess portions 45 each extend over the most of the region between twothrough-holes 46 adjacent in the first direction X.

According to the seventh modification having the above-describedstructure, the area on the first surface 17 a which is brought into incontact with the diaphragm can be further reduced by providing the thirdrecess portions. Further, the main reaction region of the electrode isthe lower surfaces of the first recesses R1 and the area of the reactionregion can be expanded by the third recess portions.

(Eighth Modification)

FIG. 29 is a partially expanded perspective view showing the firstelectrode according to the eighth modification. FIG. 30 is a plan viewof the first electrode as viewed from the first surface side.

FIG. 31 is a sectional view of the first electrode and theanion-exchange membrane, taken along line J-J of FIG. 30.

As shown in FIGS. 29 and 30, according to the eighth modification, thebasic structure of the first electrode 14 is the same as that of theseventh modification described above except that the third recessportions 45 are intermittently formed at two or more locations in thefirst direction X in the region between two through-holes 46 adjacent inthe first direction X. That is, the third recess portions 45 are formedso that the wall portion which separates the adjacent first recessportions 42 from each other remain partially. In this modification, forexample, four of the third recess portions 45 are formed in the regionbetween two through-holes 46 adjacent in the first direction X. Further,the third recess portions 45 are formed in one row along the seconddirection Y.

In the eighth modification having the above-described structure, thethird recess portions are provided intermittently, i.e., the length orwidth of each third recess portion is reduced, and thus the amount ofdeformation of the diaphragm which may warp along the first recesses R1can be reduced. Therefore, it is possible to set the positions of thediaphragm and the electrode more precisely.

Moreover, according to the eighth modification, as shown in FIG. 31, thefirst electrode 14 comprises a catalytic layer 54 formed on the firstrecess R1 except for the first surface 17 a. In other words, thecatalyst is formed on the entire first electrode 14 but the firstsurface 17 a, which is a region brought into contact with the diaphragm.With this structure, the electrolytic reaction is prohibited on thefirst surface in contact with the diaphragm, thereby making it possibleto prolong the life of the diaphragm.

Note that the eighth modification is described for the case where thethird recess portions are arranged in line along the second direction Y,but the arrangement is not limited to this. The third recess portionsmay as well be arranged to be shifted from each other in the firstdirection, or, for example, in a staggered manner.

The present invention is not limited to the embodiments andmodifications described above but the constituent elements of theinvention can be modified in various manners without departing from thespirit and scope of the invention. Various aspects of the invention canalso be extracted from any appropriate combination of a plurality ofconstituent elements disclosed in the embodiments and modifications.Some constituent elements may be deleted in all of the constituentelements disclosed in the embodiments. The constituent elementsdescribed in different embodiments may be combined arbitrarily.

For example, the first electrode and the second electrode are notlimited to rectangular shapes, but various other forms may be selected.Further, the material of each structural component is not limited tothat employed in the embodiments or modifications discussed, but variousother materials may be selected as needed. The electrode structurediscussed above may be applied not only to the first electrode but alsoto the second electrode (cathode). The electrolytic cell of theelectrode device is not limited to a three-chamber type, but it may aswell be applied to a two-chamber- or single-chamber type or anyelectrolytic cells with electrodes in general. The electrolytes andproduct are not limited to salt or hypochlorous acid, but may bedeveloped into various electrolytes and products.

What is claimed is:
 1. An electrolytic device comprising: anelectrolytic cell comprising a first electrode, a second electrodeopposing the first electrode and at least one diaphragm provided betweenthe first electrode and the second electrode, wherein the firstelectrode is formed of a plate comprising a first surface opposing thediaphragm, a second surface located on an opposite side to thediaphragm, and first recess portions formed in the first surface with afirst pattern, the first recess portions include a bottom surface apartfrom the first surface and through-holes each opening to the secondsurface of the first electrode and to a part of the bottom surface. 2.The electrolytic device of claim 1, wherein an area of the first recessportions opened in the first surface of the first electrode is 60% orlarger than an area of the first surface.
 3. The electrolytic device ofclaim 1, wherein an open aperture ratio of the through-holes is 30% orless of the area of the first surface of the first electrode.
 4. Theelectrolytic device of claim 1, wherein an open area ratio of thethrough-holes with respect to an area of the entire first surface is ahalf or less, of an opening area ratio of the first recess portions withrespect to the area of the entire first surface.
 5. The electrolyticdevice of claim 1, wherein a depth of the first recess portions is lessthan a half of a thickness of the first electrode.
 6. The electrolyticdevice of claim 5, wherein the depth of the first recess portions iswithin 0.5 mm.
 7. The electrolytic device of claim 1, wherein each ofthe first recess portion includes a plurality of through-holes eachopening to the second surface and to a part of the bottom surface of thefirst recess portion.
 8. The electrolytic device of claim 1, wherein thefirst electrode comprises second recess portion formed in the secondsurface with a second pattern different from the first pattern, and aplurality of parts of each second recess portion communicate with arespective one of the first recess portions to form the plurality ofthrough-holes.
 9. The electrolytic device of claim 8, wherein the firstrecess portions extend in a first direction, respectively, and thesecond recess portions open to the second surface and include an openingdimension in the first direction, greater than a width of the firstrecess portions, and a length of the first recess portions in the firstdirection is longer than a width of the second recess portions in thefirst direction, and a plurality of the first recess portionscommunicate with a respective one of the second recess portions to formthe through-holes.
 10. The electrolytic device of claim 9, wherein thefirst recess portions are arranged in a width direction thereof at afirst pitch, and the second recess portions are arranged in a widthdirection thereof at a second pitch greater than the first pitch. 11.The electrolytic device of claim 10, wherein the first pitch of thefirst recess portions is 0.8 mm or less.
 12. The electrolytic device ofclaim 10, wherein the second pitch of the second recess portions is 1 mmor greater.
 13. The electrolytic device of claim 10, wherein a valueobtained by subtracting the opening width W1 of the first recessportions from an arrangement pitch P1 of the first recess portions is0.3 mm or less.
 14. The electrolytic device of claim 9, wherein a depthof the second recess portions is greater than a half of the thickness ofthe first electrode.
 15. The electrolytic device of claim 9, wherein thesecond recess portions extend in a second direction different from thefirst direction.
 16. The electrolytic device of claim 15, wherein aplurality of the second recess portions communicate with a respectiveone of the first recess portions to form respective ones of thethrough-holes.
 17. The electrolytic device of claim 14, wherein thefirst recess portions extend continuously in the first direction fromone end to an other end of an effective region of the first electrodeand the second recess portions extend continuously in the seconddirection from one end to the other end of the effective region of thefirst electrode.
 18. The electrolytic devices of claim 17, wherein thefirst recess portions and the second recess portions extend linearly.19. The electrolytic device of claim 17, wherein each of the firstrecess portions is divided into plurality with gaps formed in the firstdirection.
 20. The electrolytic device of claim 18, wherein the secondrecess portions are each divided into plurality with gaps formed in thesecond direction.
 21. The electrolytic device of claim 9, wherein thesecond recess portions are constituted by through-holes penetrating thefirst electrode.
 22. The electrolytic device of claim 1, wherein thefirst recess portions include a plurality of third recess portions whichmake each adjacent pair of the first recess portions to communicate witheach other.
 23. The electrolytic device of claim 1, wherein the firstelectrode comprises a catalytic layer formed on the first recessportions except for the first surface.
 24. An electrode for use in anelectrolytic device, formed in a plate-shape, the electrode comprising:a first surface opposing a diaphragm; a second surface located on anopposite side to the first surface; and first recess portions formed inthe first surface with a first pattern; wherein the first recessportions include a bottom surface apart from the first surface andthrough-holes each opening to the second surface and to a part of thebottom surface.
 25. The electrode of claim 24, wherein an area of thefirst recess portions opened in the first surface is 60% or larger thanan area of the first surface.
 26. The electrode of claim 24, wherein anopen aperture ratio of the through-holes is 30% or less of an area ofthe first surface.
 27. The electrode of claim 24, wherein an open arearatio of the through-holes with respect to an area of the entire firstsurface is a half or less, of an opening area ratio of the first recessportions with respect to the area of the entire first surface.
 28. Theelectrode of claim 24, wherein a depth of the first recess portions isless than a half of a thickness of the electrode.
 29. The electrode ofclaim 28, wherein the depth of the first recess portions is within 0.5mm.
 30. The electrode of claim 24, further comprising second recessportions formed in the second surface with a second pattern differentfrom the first pattern, a plurality of locations of the second recessportions communicate with the first recess portions to form thethrough-holes.
 31. The electrode of claim 24, wherein the first recessportions open to the first surface and extend in a first direction, andthe second recess portions open to the second surface and having anopening length greater than a width of the first recess portions in asecond direction crossing the first direction, and a length of the firstrecess portion in the first direction is greater than a width of thesecond recess portions in the first direction and a plurality of thefirst recess portions are communicated with a respective of one of thesecond recess portions to form the through-holes.
 32. The electrode ofclaim 24, wherein the first recess portions include a plurality of thirdrecess portions which make each adjacent pair of the first recessportions to communicate with each other.
 33. The electrode of claim 24,further comprising a catalytic layer formed on the first recess portionsexcept for the first surface.